Swiss voters swung to the right in parliamentary elections on Sunday dominated by concerns over Europe's migrant crisis, with the country's largest party winning a record number of seats.

The populist Swiss People's Party (SVP), known for its virulent campaigns against immigration, the European Union and Islam, won 65 of the 200 seats in the lower house, up from the current 54, and saw its support rise to its highest-ever level.

The SVP was seen raking in 29.5 percent of the vote, compared to the 26.6 percent won in 2011 and beating its previous record score of 28.9 in 2007, the national broadcaster RTS projected.

Along with advances made by the centre-right Liberal Party, Switzerland's third-largest party, which took three additional seats on top of its current 30, SVP's gains should tip the scale in parliament from the centre-left towards a centre-right majority.

Pascal Sciarini, a political scientist at Geneva University, told AFP, that the 11 additional seats for SVP marked "a huge shift in Swiss politics," adding that "the centre of gravity has clearly shifted to the right".

"SVP did not even need to run a campaign. The migrant crisis ran the campaign for them," Sciarini said.

The Socialists, the country's second-largest party, meanwhile lost three of their 46 seats and the Greens and Green Liberal Party lost a total of nine seats.

Overall voter turnout was set at 48 percent.

- 'Send a signal' -

The shift to the right comes as surging numbers of migrants and refugees moving through Europe have heightened the focus on the issue in Switzerland, even though the wealthy Alpine nation is yet to be significantly affected by the crisis.

"We have to make Europe less attractive and send a signal that we cannot give asylum here, not even to refugees of war," SVP chief Toni Brunner told AFP.

Parties to the centre and left meanwhile lamented that the pre-election campaign had been so dominated by the migrant issue.

"People voted out of fear," Socialist candidate Rebecca Ruiz told RTS.

About a quarter of Switzerland's eight million inhabitants are foreign nationals, and immigration and asylum policies tend to figure among voters' top concerns.

But the latest survey from the gfs.bern polling institute showed that nearly 50 percent of voters considered migration the most important issue facing the country.

"I think there is a lot at stake, not only when it comes to the reception of refugees, but also the entire problem of the large numbers on the move," Colette Morel, a 69-year-old retired teacher, told AFP as she cast her ballot in the central canton of Fribourg.

In the wake of the results, French far-right politician Marine Le Pen, the leader of the country's National Front party, tweeted that "Throughout Europe, the people are saying no to the flood of migration".

- Opposition to EU ties -

Among the SVP parliamentarians already sure to take a new seat was Magdalena Martullo-Blocher in Graubunden.

She is the daughter of controversial politician Christoph Blocher, an SVP vice president who served in government from 2004-2007 before being pushed out over his extreme positions and confrontational style.

SVP members also credited the party's opposition to closer ties with the EU for its advance.

Relations with the bloc, Switzerland's top trading partner, have been badly hit by a narrow Swiss popular vote in February 2014, championed by the SVP, in favour of restricting immigration from the 28-member EU.

The centre-right Liberals are expected to cooperate with SVP on economic and energy issues but take a very different stance on other subjects, including immigration.

It remains unclear, however, what impact the shift in the lower house will have.

The makeup of the upper house, which counts 46 seats and has an equal legislative say, remains unclear, with a second round of voting required in many cantons.

In any case, power-sharing and consensus rule are the norm in Switzerland and the power balance in parliament is not directly reflected in government.

Once the new parliament is in place, it will in December elect the government, with the seven posts traditionally shared among the major parties from right to left under a tacit decades-old agreement dubbed "the magic formula", aimed at ensuring political stability.